Hmm...ugly airbox...

[beastmaster]

On some of the pictures of the bikes on this site,I've noticed that some of you have eliminated the air box completely and replaced it with high performance air filters.One on each carb.It looks really cool,and I'll bet it really contributes to performance.Are there aftermarket setups available?Or did you ingenious folks just find some other way? ;D
What alterations does a guy have to make to the vacume routing and what about a crankcase breather?
Sunny,warm beautiful day here on Canada's west coast.......
 :(And me without my ride...

[ProfessorRex]

I don't think anyone has had much success doing that.  As is, the stock airbox setup is able to flow more air than the engine can use.  I know that  it would require bigtime jetting changes... a lot of tuning work... and plenty of luck!  Oh and as far as looking cool... they'd be entirely covered by the gas tank, though you would DEFINATELY hear the difference, the intake sound would be LOUD.  Probably louder than a set of mac's.

Hopefully one of the guys(or gals) who's tried this will get on this post.

-Rex

[beastmaster]

LOL ;D ;D
I know they'd be covered!!But I'd still know how cool they look!!LOL ;D ;D
Whatever y'all can tell me! ;)

[louthepou]

Yeah, I too think it's not worth the trouble. A finely tuned Vision with the stock airbox wouldn't gain a whole lot from switching to a set of K and N filters.

My 2 cents,

Louis

[beastmaster]

Why would the front of my air box have duct tape all over it? :-/
I was looking at this last night.Do I need the update if I decide to use it again?

[Walt_M.]

Ok, one more time. The Vision airbox has the flapper in it to reduce air volume at low rpm. This is to increase intake velocity through the carbs because they are relatively large for the engine size. If you put low restriction air filters on, you will have problems, 'Vision Stumble' being most immediate and hardest to fix. If you want to increase performance, put a free flowing exhaust on it. There are a couple of choices, probably Macs are more readily available.

[Blake]

I've probably gotten the furthest along on this subject while trying to do it in a precise manner.  But as everyone has said.  its not worth the time to put free flowing filters (K&N pods in my case) on.     I have a AFR meter that they would use as shops to help tune your bike for you, and its still giving me troubles.  It really is a "guess and check" system.  As far as stumble, by removing the airbox you remove the "CV" system the designers tried to implement as an afterthought, and essential have a crude downdraft version of a "roundslide carb."  although nice for high rpm racing applications, you really do have to baby it when accelerating because your wrist now performs the function of that flapper on the airbox-regulating airflow to exactly what the engine needs.  On my setup I also have a nice free flowing custom exhaust which seems to help with the whole "more in air/more air out" concept.  But still.  Unless your willing to dedicate lots of money (and more importantly time..dont get me started on the time involved-taking tank off, changing jets, put tank on, set up equipment to go for test ride, ride and record info, go back and look at info...it just goes on)  your best best is to stick with the stock airbox.  And with a stock exhaust setup, you really cant get any better perfomance than what the factory gives you.



just my bit of info.

Blake

[beastmaster]

Ok.I'm convinced!If it ain't broke,don't fix it!I'll keep it stock.Thanks everyone for the valueable info.Truth is,when the carbs are clean and the bike is tuned,it works just fine.

[h2olawyer]

Why would the front of my air box have duct tape all over it?  

Good question.  Maybe a previous owner was under the same misconception that putting some holes in the airbox, increasing air volume, would improve performance.  Dennis Kirk does sell a foam filter for the Vision (made by Uni-Filter).  This is about the only airbox / intake modification that is worthwhile, and then mainly for the ease of cleaning & not needing to find a new one when needed.

H2O

[Lucky]

you could allways pull the tape off & see what's underneath..or pull the top off the airbox & look to see if there are holes, cracks, etc. ?if you don't have the vacuume operated door, then you don't have the update installed. if this is the case, than that was probably someones attempt at reducing the amount of air entering the carbs. not a very effective way to do it...
--Lucky

[beastmaster]

Well,there's a big hole there.So I'll look further in to it.You guys are most likely right.It's a very early 82.Production date 12/81.Last four #'s in the VIN are 1023...23,I think!Or 26 maybe.Can't remember.LOL 8)
Anyway,looks like I need to get the update.It's gonna have to wait till I get this other stuff done though. ::)

[MotorPlow]

You had better get the update now as there is one on eBay.  They are no longer made and extremely rare.  If you don't get it now, there is no telling when there will be another available.

[Lucky]

I have everything needed to do the update. used stuff but works just fine. when he's ready I should still have it.
--Lucky

[Extent]

I don't know if the Vision airbox is tuned or not, but it is sealed at the least.  The benifit of an airbox is in getting it to resonate, you can change the frequency that to box resonates by changing it's volume and the length and area of the intake pipes.  When the bike is revving at the RPM that the box is tuned for what you get is every intake cycle falls on a point where the pressure in the airbox goes high.  Youre supposed to be able to see a 10 to 15% increse in power in the tuned range with this effect, and manufacturerers use this to smooth out peaks in the RPM range.  In order for it to work the airbox must be completely sealed and rigid.  They apparently started doing this in the "mid eighties" so take it with a grain of salt.

[beastmaster]

Thanks Lucky.Good to know.Great website,by the way.It's helped me with a lot of things.
So far no one has bid on the one on e-bay.I'll keep watching it.There's still three days left.
When you talk about tuning your airbox,you're talking about a modified one or an early style one. ???

[Extent]

I'm talking about mostly conceptual stuff.  The people doing the tuning would be Yamaha when they made the bike.  The airbox is very likely there to smooth out the torque curve, so removing it completely for cone filters wouldn't have any positive effect, even cutting holes in it to let more air in could render it ineffective.

[beastmaster]

Well,that explains why there's a whole shwag of duct tape over the BIG hole that some previous owner hacked in to the airbox!
Upon closer inspection,I've determined that I do have the updated airbox.One less hunt!
Duct-tape anyone?LOL

[Superfly]

Has anyone used the dennis kirk air filter,  Mine has seen better days..... and does it work better with an aftermarket exhaust, or the stock exhaust?

[h2olawyer]

If you're talking about the Uni-Filter from Dennis Kirk, that's what I'm using now.  It seems to work well.  Mine seemed to rev just a little freer after I installed it.  Not a big difference - maybe just my imagination as I could feel no appreciable difference.  If you oil the filter, make sure you use foam filter oil & not K&N oil.  You don't want the red oil running out the carb box drain holes and all over the engine.  That stuff stinks when it burns.   ::)  The K&N oil is much thinner than the stuff made for foam filters.